JPS6211336Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a leakage prevention structure for a cross-flow water turbine in which leakage water flowing out of the casing along the rotation axis of the runner is returned into the casing.

FIG. 1 is a partially cutaway perspective view showing a typical structure of a cross-flow water turbine, in which a runner 1 rotated by the potential energy of water is rotatably supported within a casing 2. Casing 2
The runner 1 is supported by the rotating shaft 3 of the runner 1 supported on the casing 2 side via a bearing 4. An inlet pipe 5 is connected to the casing 2 on the upstream side of the runner 1,
A guide vane 6 for adjusting the amount of water entering the runner 1 is provided on the inlet side of the casing 2 corresponding to the outlet side of the inlet pipe 5 so as to be openable and closable. Also,
Another casing (cover) 7 is connected to the casing 2 on the downstream side of the runner 1, and a water discharge pipe 8 hanging down from these casings 2 and 7 is connected. Therefore, when the crossflow turbine is operated, water flowing in from the inlet pipe 5 is adjusted by the guide vane 6, enters the runner 1, rotates the runner 1, and is discharged from the outer periphery of the water discharge pipe. 8 to be discharged into the water.

On the other hand, when the cross-flow turbine is operated and starts discharging water, air is mixed in and discharged, creating a negative pressure inside the turbine chamber made up of the casings 2 and 7. acts as a force to forcibly draw in water, thereby improving the efficiency of the water wheel. When the water turbine chamber becomes negative pressure, the water discharge surface of the water discharge pipe 8 rises, but it would be bad if the water discharge surface rose to the extent that the runner 1 was submerged, so adjust the negative pressure inside the water turbine chamber to adjust the water discharge surface appropriately. For this purpose, an air valve 9 is installed on the cover 7. In other words, when the negative pressure inside the water turbine chamber reaches a predetermined value, the air valve 9
opens to introduce air into the turbine chamber, and is configured to prevent the negative pressure inside the turbine chamber from exceeding a certain set value.

However, until the water discharge pipe 8 is filled with water when the water turbine starts operating, negative pressure cannot be established in the turbine chamber, and the pressure inside the turbine chamber becomes positive due to the inflow of water. As a result, water leaks from the bearing 4 to the outside along the rotating shaft 3. To deal with this problem, in the past, in order to prevent water from leaking from the rotating shaft 3, the leaking part, that is, the penetrating part of the casing 2 that supports the rotating shaft 3, was filled with gland packing. Even if it is possible to prevent water leakage by providing a packing, water is rarely splashed between the gland packing and the rotating shaft 3 during operation, so cooling is not achieved and friction torque is generated, which causes damage to the runner. This will have an adverse effect on the rotation of 1. In addition, the gland packing wears out and requires additional tightening, and when it becomes obsolete, it must be replaced, causing various problems in terms of maintenance and inspection.

In order to eliminate the drawbacks of the conventional structure, the present invention aims to provide a structure for preventing water leakage from the rotating shaft penetrating part of a cross-flow water turbine, which can prevent water from leaking from the rotating shaft and improve operational efficiency. The structure of the present invention to achieve this purpose is as follows:
In a cross-flow water turbine in which a rotating shaft having a runner passes through a bracket provided in a casing forming a water turbine chamber and protrudes outward from the casing, a rotating shaft is provided at a portion of the bracket through which the rotating shaft passes. A cylindrical part surrounding the rotary shaft is provided at both ends of the cylindrical part, and a labyrinth part is provided at each end of the cylindrical part to seal the rotary shaft, an air chamber is formed in the cylindrical part between the two labyrinth parts, and a rotary shaft is provided on the water turbine chamber side of the cylindrical part. A draining plate is provided which rotates integrally with the air chamber, and an air inlet is provided in the upper part of the air chamber, and a water drain hole is provided in the lower part of the air chamber, so that the inside of the air chamber is maintained at approximately atmospheric pressure.

Hereinafter, one embodiment of the water leakage prevention structure for a cross-flow water turbine according to the present invention will be described in detail based on FIG. 2.

A drain plate 10 having an annular convex portion 10a located inside the bearing is fixed to the rotating shaft 3 to which the runner 1 is fixed, and rotates integrally with the rotating shaft 3. Further, the bracket 11 is provided in a casing 2 forming a water turbine chamber, and the rotating shaft 3 passes through the bracket 11. A cylindrical portion 22 surrounding the rotating shaft 3 is provided at the portion of the bracket 11 through which the rotating shaft 3 passes, and labyrinth portions 12 and 13 are formed at both ends of the cylindrical portion 22 to seal the rotating shaft 3, respectively. There is. The air chamber 14 is formed between the labyrinth parts 12 and 13, and is an annular groove having a larger inner diameter than the labyrinth parts 12 and 13. That is, along the axial direction of the rotating shaft 3, the labyrinth portion 12 and the air chamber 1 extend from the inside of the casing 2 to the outside.
4 and labyrinth portion 13 are formed in this order.
The bracket 11 also has a convex portion 1 of the draining plate 10.
An annular groove 21 that fits into the groove 0a is formed.

An air inlet 14a that communicates with the outside air is provided above the air chamber 14, and a horizontal pipe 16 that maintains the inside of the air chamber 14 at atmospheric pressure is connected via a nipple 15. Further, a drain hole 14b is provided below the air chamber 14, and a drain pipe 18 is connected via a nipple 17 so as to communicate from the concrete floor 19 to a water discharge channel (not shown).

Note that 20 in the figure is a draft pipe that communicates with water discharge pipes, etc. During normal operation of the water turbine, draft pipe 2
A negative pressure is generated in the water turbine chamber inside the bracket 11 due to the suction effect of 0.

Therefore, during operation of the cross-flow water turbine configured in this manner, water droplets flying from the runner 1 are first blown off by the draining plate 10, and then flow between the convex portion 10a and the groove 21 of the draining plate 10. , and the labyrinth part 1 of the labyrinth structure with the rotating shaft 3
2 and enters the air chamber 14. The water droplets that have entered the air chamber 14 collect at the bottom and are discharged from the drain hole 14b through the drain pipe 18 to the underfloor. That is, when the water turbine is started, water flows into the water turbine chamber from the inlet pipe 5, and the air in the water turbine chamber is released, creating a positive pressure. It is discharged to the outside from the inlet 14a through the pipe 16. Also, during normal operation of the water turbine, the draft pipe 2
Due to the suction effect of 0, negative pressure is generated inside the water turbine chamber, air in the air chamber 14 is sucked into the water turbine chamber via the labyrinth part 12, and outside air is sucked in from the air inlet 14a. In this state, the rotating shaft 3
Since the draining plate 10 is also rotating together with the runner, water droplets flying from the runner 1 are also blown away by the centrifugal force, and most of the water droplets are transferred to the labyrinth section 12.
This prevents the air from entering the air chamber 14. In addition, any water droplets that have entered are discharged from the water drain hole 14b to the underfloor, so that water does not leak to the outside of the rotary shaft 3.

As described above in detail based on the embodiment shown in the drawings, according to the water leakage prevention structure according to the present invention, a labyrinth part having a labyrinth structure is provided in the bracket extending from the casing, and the labyrinth part of the labyrinth part is In addition to installing a drain plate on the water turbine side,
It has a simple structure with a large air chamber on the outside of the drain plate, an air inlet open to the atmosphere at the top of the air chamber, and a drain hole at the bottom, and the pressure in the air chamber is maintained at approximately atmospheric pressure. As a result, all water leaking from the water turbine chamber is discharged from the water drain hole in the air chamber to the discharge channel, preventing water from leaking to the outside.

In addition, during normal operation of the water turbine, negative pressure is generated inside the water turbine chamber due to the suction effect of the draft pipe, which improves the flow of water from the inlet pipe and the water discharge from the water discharge pipe, which improves the efficiency of the water turbine. It produces the above effect.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a typical structure of a cross-flow water turbine, and FIG. 2 is a sectional view of a main part showing an embodiment of the leakage prevention structure of a cross-flow water turbine according to the present invention. In the drawing, 1 is a runner, 2 is a casing, 3 is a rotating shaft, 10 is a draining plate, 11 is a bracket, 1
2 and 13 are labyrinth parts, 14 is an air chamber, 1
4a is an air inlet, 14b is a drain hole, 16 is a pipe, 18 is a drainage pipe, 19 is a concrete floor,
20 is a draft pipe.

Claims (1)

[Scope of utility model registration request] In a cross-flow water turbine in which a rotating shaft having a runner passes through a bracket provided in a casing forming a water turbine chamber and protrudes outward from the casing, a rotating shaft is provided at a portion of the bracket through which the rotating shaft passes. A cylindrical part surrounding the rotary shaft is provided at both ends of the cylindrical part, and a labyrinth part is provided at each end of the cylindrical part to seal the rotary shaft, an air chamber is formed in the cylindrical part between the two labyrinth parts, and a rotary shaft is provided on the water turbine chamber side of the cylindrical part. A leakage cross-flow water turbine characterized in that a drain plate is provided which rotates integrally with the air chamber, an air inlet is provided in the upper part of the air chamber, and a drain hole is provided in the lower part of the air chamber so that the inside of the air chamber is maintained at approximately atmospheric pressure. Water-proof structure.